1. Field of the Invention
The present invention relates to a solenoid actuated gas valve.
2. Description of Related Art
It is desirable to provide an alternate fuel(s) to gasoline and diesel for internal combustion engines. One alternate fuel candidate is natural gas. Natural gas typically generates less pollutants and is generally less expensive than gasoline or diesel.
The flow of natural gas within an internal combustion engine must be controlled by a valve(s). Conventional gas valves contain a poppet, ball or needle valve that is moved into an open position by a solenoid. The solenoid is typically located within a cavity that is exposed to the natural gas flowing through the valve. The gas may pick up microscopic metal particles from the fluid lines. These metal particles become attracted to the magnetic material of the solenoid. The metal particles may become attached to the magnetic material and create a film that degrades the performance of the solenoid. Additionally, oils and water in the gas which come into contact with the solenoid may gum and/or corrode the solenoid components over time. It would be desirable to provide a solenoid actuated gas valve that seals the solenoid from the gas.
Present gas valves are typically pressure unbalanced so that the pressure of the gas tends to maintain the valve in the closed position. The biasing force of the gas pressure requires additional force to open the valve, thereby reducing the energy efficiency of the device. The biasing force of the gas pressure can be lowered by reducing the area of the valve seat. Reducing the seat area increases the stress on the valve and reduces available flow area. The additional stress can accelerate material wear. The material wear will enlarge the seat opening and change the flowrate through the valve over time. Material wear at the seat will also increase the valve lift and also change the flowrate through the valve over time.
To prevent material wear and failure, present gas valves are typically constructed from hard metal materials. It has been found that the interface between the valve seat and a hard valve may have microscopic channels even when the valve is in the closed position. The microscopic channels allow gas to leak therethrough. When used in an internal combustion engine the gas can leak into the combustion chamber during the power and exhaust strokes, resulting in the emission of uncombusted natural gas. It would be desirable to provide a gas valve that has a truly sealed valve seat, produces a relatively constant flowrate through the valve over the life of the valve, has a performance which is independent of gas pressure, and isolates the solenoid portion of the valve device from contact with the gas medium to prevent solenoid contamination and premature failure.